The present invention relates to an apparatus and method for detecting α-rays using a semiconductor detector made of silicon or the like, particularly suitable for reducing a time required for measuring the α-rays.
A PR gas-based gasflow counter has been known as a device for measuring a trace of α-rays contained in a sample. This type of counter tube is described, for example, in “Radiation Handling Techniques”, Japan Atomic Industrial Forum, edited by Japan Atomic Industrial Forum, pp. 224–225, May 26, 1998.
A semiconductor-based detector using a semiconductor detector has been also known as an α-ray measuring apparatus which is capable of analyzing energy. This type of detector is described, for example, in JP-A-10-213666, particularly on page 2 and in FIG. 1.
The gasflow counter is suitable for capturing α-rays in measurements of a trace of α-rays emitted from a sample because it is readily provided with a larger area for the capture. However, this type of counter tube exhibits a low dependency on the energy of the α-rays emitted from the sample, and a low energy resolution.
The solid state (semiconductor) detector, on the other hand, exhibits a high energy resolution. Disadvantageously, however, the semiconductor detector has a small sensitive area, with difficulties in increasing the sensitive area, and therefore takes a long measurement time for accurately measuring a trace of α-rays.
Also, for accurately measuring the α-ray in a short time, it is necessary to sufficiently remove background noise due to cosmic radiations and electric disturbance. A sufficiently thick shielding material must be provided for removing the background noise to a predetermined level, resulting in a cumbersome and heavy α-ray measuring apparatus as a whole.